The present invention relates to a paint peeling composition and a paint peeling method for peeling off hardened or unhardened paint adhered to objects not to be painted such as a duckboard, a floor, a table for mounting thereon an object to be painted and a cover of an automatic coater placed at a work place for painting.
Known methods for peeling off a thermosetting resin paint and the like adhered to an object not to be painted are as follows:
(a) An object not to be painted is pre-coated with a paint peeling composition including as effective components thereof a thermoplastic resin paint and an organic solvent. Unnecessary paint adhered to this coating is peeled off by cracking the coated surface with a hammer and the like (Japanese patent application published or laid open under SHOWA 57-195774). PA1 (b) The object not to be painted is pre-coated with a paint peeling composition including as effective components thereof coating-forming material and a water-absorbent polymer. When unnecessary paint adhered to this coating is water-washed, the water-absorbent polymer reacts with the water and then absorbs much of the same. A volumetric expansion of a ratio of tens or hundreds times associated with this water absorption serves to float the adhered unnecessary paint off the object not to be painted and thereafter the floated paint is peeled off with a pallet, pliers, a hammer, a drill and the like (Japanese patent application published or laid open under SHOWA 57-19067). PA1 (c) The adhered unnecessary paint is peeled off by being burnt in a burner and the like. PA1 (d) The adhered unnecessary paint is peeled off by being re-solved by an organic solvent. PA1 (e) The unnecessary paint is peeled off by being submerged in boiling caustic soda for approximately 12 hours to cause a chemical reaction therein. PA1 (f) The unnecessary paint is scraped off by a metallic pallet and the like. PA1 (a) Much of the mechanical impact applied to the coated surface is absorbed into the object per se through the coating. Therefore, a considerable impact is needed to cause the paint to crack. PA1 (c) This method is unfeasible for an unmovable object such as the floor of the work place and for an object subject to thermal transformation or to thermal solution. Moreover, this method tends to cause smoke pollution or toxic gases such as nitrogen oxides. PA1 (d) This method is unfeasible for an immovable object such as the floor of the work place and for a pre-painted object such as the cover of the automatic coater. PA1 (e) According to this method, the peeling operation is very time consuming. And, moreover, the object need undergo a neurtalization process after the paint peeling operation; otherwise, the object may incur rust. In addition, the caustic soda may pose human health hazard, and the waste liquid disposal of the caustic soda used for the peeling operation is very costly. PA1 (f) According to this method, if the adhered paint is a viscous, unhardened paint, the scraping operation is very labor-consuming.
Problems with the above methods will be respectively discussed hereinafter.
(b) The contact between the water-absorbent polymer and the water needed for the chemical reaction is interfered with by the coated surface. Or, if the paint peeling composition is pre-coated at a high temperature (about 300.degree. C.), the water-absorbent polymer is carbonized to such an extent that it loses its water-absorbing expansion characteristics. Furthermore, this method is unfeasible for a water base paint including water such as a water solbule paint or a water-dilutable emulsion paint.